Coatings May Make Rooms Self-Cleaning

Photonics.comFeb 2006
SYDNEY, Australia, Feb. 8, 2006 -- Cleaning bathrooms by hand may become a thing of the past, now that new nanotechnology-based coatings are being developed to do the work for you, say researchers at the University of New South Wales (UNSW) in Sydney. The scientists are developing coatings they hope will be used for self-cleaning surfaces in locations such as hospitals and homes. Led by professors Rose Amal and Michael Brungs of the ARC Centre for Functional Nanomaterials, a team is studying tiny particles of titanium dioxide currently used on outdoor surfaces such as self-cleaning windows.

The particles work by absorbing ultraviolet light below a certain wavelength, exciting electrons and giving the particles an oxidizing quality stronger than any commercial bleach. These nanoparticles then kill microbes and break down organic compounds. And because surfaces coated with titanium dioxide have another property called "superhydrophilicity," meaning droplets do not form, water runs straight off the surface, washing as it goes.

Manually cleaning a bathroom could one day be obsolete thanks to nanocoatings.At present, titanium dioxide can only be activated by the ultraviolet A present in sunlight. But the UNSW team is working on ways to activate titanium dioxide with indoor light. The team is modifying titanium dioxide nanoparticles with other elements such as iron and nitrogen so they can absorb light at longer wavelengths.

Lab trials show that glass coated with the new nanoparticles can be activated by visible light from a lamp to kill E. coli bacteria. "If you've got this on tiles or shower screens you don't need so many chemical agents," said Amal.

So far the team has been working at laboratory scale. "It's probably a year before we can talk to industry and test outside the lab," she said.